Magnetic Tunnel Junction Device and Fabrication

ABSTRACT

A magnetic tunnel junction (MTJ) device and fabrication method is disclosed. In a particular embodiment, a method of forming a magnetic tunnel junction (MTJ) device includes forming a top electrode layer over an MTJ structure. The top electrode layer includes a first nitrified metal.

I. CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of and claims priorityunder 35 U.S.C. §120 from commonly-owned, co-pending U.S. patentapplication Ser. No. 12/548,678 filed Aug. 27, 2009, entitled “MAGNETICTUNNEL JUNCTION DEVICE AND FABRICATION,” which application isincorporated by reference herein in its entirety.

II. FIELD

The present disclosure is generally related to magnetic tunnel junction(MTJ) devices and fabrication.

III. DESCRIPTION OF RELATED ART

MTJ elements may be used to create a magnetic random access memory(MRAM) or a spin torque transfer MRAM (STT-MRAM). An MTJ elementtypically includes a pinned layer, a magnetic tunnel barrier, and a freelayer, where a bit value is represented by a magnetic moment in the freelayer. A bit value stored by an MTJ element is determined by a directionof the magnetic moment of the free layer relative to a direction of afixed magnetic moment carried by the pinned layer. The magnetization ofthe pinned layer is fixed while the magnetization of the free layer maybe switched.

When fabricating the MTJ element, oxidation may occur at various processstages. For example, etching the MTJ layers to form the MTJ element maycause an oxidation layer to form if the etch chemical includes oxygen.Removal of the oxidation layer to reduce series resistance can requiremore pre-cleaning and over-etching. However, the MTJ top contact openinghas a narrow process window to remove the top oxidation layer due to thewafer topography and etch uniformity issues. Increasing a pre-sputterclear process of the top electrode of the MTJ element may cause moreloss of the top layer of the MTJ layers at the center region of thewafer, which may reduce process margins. Advanced low-k film stackrestrictions may limit a pre-clean and pre-sputter process, furtherreducing an MTJ process window.

IV. SUMMARY

The MTJ fabrication process may be modified to include a conductivenitrified metal in the top electrode layer, an MTJ cap layer, or both.The nitrified metal is conductive and exhibits less oxidation thantraditional top electrode layer and MTJ cap layer materials. The reducedoxidation due to the nitrified metal enables an MTJ process integrationand process window to be increased.

In a particular embodiment, a method of forming a magnetic tunneljunction (MTJ) device is disclosed. The method includes forming a topelectrode layer over an MTJ structure. The top electrode layer includesa first nitrified metal. The first nitrified metal may be tantalumnitride (TaN) or titanium nitride (TiN) as illustrative, non-limitingexamples. Because TiN and TaN are common barrier materials used in aback end of line (BEOL) process for VLSI, TiN and TaN may be easilyimplemented.

In another particular embodiment, an apparatus is disclosed thatincludes a magnetic tunnel junction (MTJ) device. The MTJ deviceincludes an MTJ structure and a top electrode layer coupled to the MTJstructure. The top electrode layer includes a first nitrified metal.

In another particular embodiment, the apparatus includes a magnetictunnel junction (MTJ) device including an MTJ structure and an MTJ caplayer coupled to the MTJ structure. The MTJ cap layer includes a singlelayer, the single layer including a nitrified metal.

One particular advantage provided by at least one of the disclosedembodiments is a reduced amount of oxidation at one or more processsteps of fabricating an MTJ device as compared to conventional devicesthat do not include a nitrified top electrode layer or nitrified MTJ caplayers. Reduced oxidation enables an MTJ process integration and processwindow to be increased. Other aspects, advantages, and features of thepresent disclosure will become apparent after review of the entireapplication, including the following sections: Brief Description of theDrawings, Detailed Description, and the Claims.

V. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a first illustrative diagram of a system including a magnetictunnel junction (MTJ) device having a top electrode layer with nitrifiedmetal;

FIG. 2 is a second illustrative diagram of a system including a magnetictunnel junction (MTJ) device having a top electrode layer with nitrifiedmetal;

FIG. 3 is a third illustrative diagram of a system including a magnetictunnel junction (MTJ) device having an MTJ cap layer with nitrifiedmetal;

FIG. 4 is a fourth illustrative diagram of a system including a magnetictunnel junction (MTJ) device having an MTJ cap layer with nitrifiedmetal;

FIG. 5 is a fifth illustrative diagram of a system including a magnetictunnel junction (MTJ) device having a top electrode layer, an MTJ caplayer, and a bottom electrode layer with nitrified metal;

FIG. 6 is a flow diagram of a first illustrative embodiment of a methodof forming a magnetic tunnel junction (MTJ) device;

FIG. 7 is a flow diagram of a second illustrative embodiment of a methodof forming a magnetic tunnel junction (MTJ) device;

FIG. 8 is a block diagram of a particular embodiment of a portablecommunication device including a component including MTJ structureshaving top electrode layers or MTJ cap layers with nitrified metal; and

FIG. 9 is a data flow diagram illustrating a manufacturing process foruse with magnetic tunnel junction (MTJ) devices including MTJ structureshaving top electrode layers or MTJ cap layers with nitrified metal.

VI. DETAILED DESCRIPTION

Referring to FIG. 1, a first embodiment of a system including a magnetictunnel junction (MTJ) device 100 is depicted. The device 100 includes anMTJ structure 106 coupled to a top electrode 120, such as via an MTJ caplayer 116. The top electrode 120 includes a first conductive nitrifiedmetal. The first conductive nitrified metal is resistant to oxidationand enables formation of a top via and top metal wire 122 with a relaxedprocess window. The first conductive nitrified metal may be tantalumnitride (TaN), or titanium nitride (TiN), or another nitrified metalthat exhibits the properties of being conductive and resistant to oxideformation.

As illustrated, the device 100 may include a bottom metal wire 102 and abottom cap film deposited over the bottom metal wire 102. A bottomelectrode 104 may be coupled to the bottom cap film and electricallycoupled to the bottom metal wire 102 via a via through the diffusionbarrier cap film. The MTJ structure 106 is deposited over the bottomelectrode 104. As illustrated, the MTJ structure 106 includes ananti-ferromagnetic (AFM) layer 108. A fixed layer 110 may be coupled tothe AFM layer 108. A tunnel barrier layer 112 may be coupled to thefixed layer 110, and a free layer 114 may be coupled to the tunnelbarrier layer 112. The MTJ cap layer 116 may be between the MTJstructure 106 and the top electrode 120 and coupled to the top of theMTJ structure 106. A sidewall protective layer 118, such as a siliconnitride (SiN) diffusion barrier, may be formed adjacent to the sidewallsof the MTJ structure 106 and the MTJ cap layer 116. The top electrode120 has a bottom surface that may be coupled to the MTJ cap layer 116and a top surface coupled to the top via and top metal wire 122. The topelectrode 120 includes a first nitrified metal, such as tantalum nitride(TaN) or titanium nitride (TiN).

The top electrode 120 including the first nitrified metal enablesformation of the device 100 with a larger process window for connectingthe top via and top metal 122 to the top electrode 120. To illustrate,during fabrication, the top electrode 120 including the first nitrifiedmetal may be formed by depositing electrode material including the firstnitrified metal to form a top electrode layer and patterning the topelectrode. The top electrode 120 may be surrounded by an inter-metaldielectric (IMD). The top via and metal wire 122 connected to the topelectrode 120 may be formed using a damascene process that involvesforming a trench in the IMD for the top metal wire 122 and forming a topvia from the bottom of the trench to the top electrode 120 fordeposition of via material, such as illustrated in FIG. 1. The top canbe removed if the MTJ stack closes to via height. During the damasceneprocess, an oxidation can occur at the exposed surface of the topelectrode 120. The oxidation may result in an increased surfaceresistance at the surface of the top electrode 120 and degradation ofdevice performance. However, by including the first nitrified metal inthe top electrode 120, a reduced amount of oxide may form on the uppersurface of the top electrode 120 during processing as compared to anon-nitrified metal. To illustrate, tantalum nitride and titaniumnitride are examples of conductive nitrified metals. Titanium nitride ismore resistant to oxidation than titanium, and tantalum nitride is moreresistant to oxidation than tantalum.

The first nitrified metal in the top electrode 120 enables the formationof the device 100 including the connection of the top electrode 120 tothe top via and top metal wire 122 with an increased process window. Asa result, additional cleaning steps may be reduced or removed or adependence on a cleaning process may be reduced. Performance of theillustrated device 100 as a memory storage device may be enhanced due toa lower electrical resistance at the interface between the top electrode120 and the via to the top metal 122 due to use of the first nitrifiedmetal. Also, an MRAM yield may be improved due to an enhanced processwindow.

Referring to FIG. 2, a second embodiment of a system including an MTJdevice 200 coupled between a bottom metal wire 202 and a top metal wire222 is depicted. The device 200 includes a lower diffusion barrier capfilm deposited over the bottom metal wire 202 and electrically coupledto a bottom electrode 204 via a bottom via through the diffusion barriercap film. An MTJ structure 206 is formed on the bottom electrode 204.The MTJ structure 206 includes an AFM layer 208, a fixed layer 210, atunnel barrier layer 212 between the fixed layer 210 and a free layer214, and an MTJ cap layer 216. A protective sidewall 218 at leastpartially encases or encloses the MTJ structure 206 and the MTJ caplayer 216.

The top electrode 220 is coupled to the MTJ cap layer 216. The topelectrode 220 includes a first electrode layer 230 of non-nitrifiedconductive material, such as tantalum, titanium, or anothernon-nitrified conductive material, that is coupled to the MTJ cap layer216. The top electrode 220 also includes a second electrode layer 232including the first conductive nitrified metal. The top metal wire 222is coupled to the second electrode layer 232 via a top via and an upperdiffusion barrier cap film is deposited over the top metal wire 222. Aninter-metal dielectric (IMD) encloses the MTJ device and the top metalwire 222.

In a particular embodiment, the top electrode 220 includes the firstelectrode layer 230 and the second electrode layer 232. However, inanother embodiment, the top electrode 220 may include more than twolayers. As illustrated, the non-nitrified conductive material of thefirst electrode layer 230 enables low-resistance electrical contactbetween the MTJ cap layer 216 and the second electrode layer 232. Thesecond electrode layer 232 includes a first conductive nitrified metal,such as tantalum nitride, titanium nitride, or other conductivenitrified metal that exhibits the properties of being conductive andresistant to oxide formation. As a result of the second electrode layer232 including the first nitrified metal, the electrical connectionbetween the top electrode 220 and the top metal 222 is not significantlyimpaired by formation of oxide on the upper surface of the secondelectrode layer 232, as compared to electrical connections of MTJdevices not including the first nitrified metal. Therefore, a processwindow may be increased by less pre-clean and device yield may be lessaffected by the lessened cleaning process of the top electrode 220.

In a particular embodiment, the first electrode layer 230 consistsessentially of material other than the first conductive nitrified metal.To illustrate, the top electrode 220 may be formed by depositing atantalum material without including tantalum nitride during depositionof the first electrode layer 230. After formation of the first electrodelayer 230, the second electrode layer 232 may be formed on the firstelectrode layer 230. The second electrode layer 232 may be formed bydepositing tantalum nitride material to form a layer that primarilyincludes tantalum nitride. As a result, the first electrode layer 230may consist essentially of materials other than tantalum nitride, whilethe second electrode layer 230 may primarily include tantalum nitride.As another example, a similar formation process may be performed usingtitanium in the first electrode layer 230 and titanium nitride in thesecond electrode layer 232. In other embodiments, another nitrifiedmetal that is conductive and resistant to oxide formation may be used inthe second electrode layer 232 and the first electrode later 230 mayprimarily include conductive material other than the nitrified metal. Inyet another embodiment, Ruthenium (Ru) may be used in place of, or inaddition to, nitrified metals. Ruthenium is conductive and oxidation ofRuthenium is also conductive. As a result, use of Ruthenium can reduce apre-clean process without increasing interconnection resistance.Embodiments using ruthenium or alloys including ruthenium arespecifically contemplated in the present disclosure.

Referring to FIG. 3, a third embodiment of a system including an MTJdevice 300 is depicted. The MTJ device 300 includes an MTJ structure 306coupled to an MTJ cap layer 316 that includes nitrified metal. Thedevice 300 includes a bottom metal wire 302 that is coupled to a bottomelectrode 304 via a bottom via through a bottom diffusion barrier capfilm layer. The MTJ structure 306 is coupled to the bottom electrode304. The MTJ structure 306 includes an AFM layer 308, a fixed layer 310,a tunnel barrier layer 312, and a free layer 314. The MTJ cap layer 316with the conductive nitrified metal is coupled to the free layer 314. Atop electrode 320 is coupled to the upper surface of the MTJ cap layer316 and is electrically coupled to a top metal line 322 via a conductivepath or via. A top diffusion barrier cap film is illustrated over thetop metal wire 322 and over an inter-metal dielectric.

The MTJ cap layer 316 includes a single layer, the single layerincluding conductive nitrified metal, such as the first conductivenitrified metal of the top electrode 120 of FIG. 1 or the top electrode220 of FIG. 2 to provide benefits with regard to oxidation and surfaceconductivity as described above. In a particular embodiment, theconductive nitrified metal of the MTJ cap layer 316 includes a metalnitride, such as tantalum nitride or titanium nitride, or anycombination thereof. Including nitrified metal in the MTJ cap layer 316enables a fabrication process window to be increased. For example,during formation of the MTJ device 300, the MTJ cap layer 316 serves asa protective layer to the MTJ structure 306 beneath the MTJ cap layer316. However, during an MTJ etching process, oxidation may occur at theupper surface of the MTJ cap layer 316. As a result of using nitrifiedmetal in the MTJ cap layer 316, an impact of oxidation on the surface ofthe MTJ cap layer 316 may be reduced or eliminated. The top electrode320 may therefore be formed on the MTJ cap layer 316 with a reducedamount of cleaning of the upper surface of the MTJ cap layer 316, with arelaxed process tolerance for formation of the top electrode 320, orboth. The top electrode 320 may include a second nitrified metal. Insome embodiments, the second nitrified metal may be the same as theconductive nitrified metal of the MTJ cap layer 316, while in otherembodiments the second nitrified metal may be different from theconductive nitrified metal of the MTJ cap layer 316.

Referring to FIG. 4, a fourth embodiment of a system including an MTJdevice 400 using conductive nitrified metals is depicted. Asillustrated, the device 400 includes an MTJ cap layer 416 including atleast two layers illustrated as a first MTJ capping layer 434 and asecond MTJ capping layer 436 over the first MTJ capping layer 434. Asillustrated, the first MTJ capping layer 434 is in contact with theupper surface of a free layer 414 and includes non-nitrified material.The second MTJ capping layer 436 is coupled to an upper surface of thefirst MTJ capping layer 434 and includes conductive nitrified metal. Thenitrified metal of the second MTJ capping layer 436 provides benefitssimilar to the benefits described with respect to the MTJ cap layer 316of FIG. 3. The device 400 also includes components similar tocorresponding components of the device 300 of FIG. 3, including a bottommetal wire 402, a bottom electrode 404, a top electrode 420, a top metalwire 422, and an MTJ structure 406 including an AFM layer 408, a fixedlayer 410, a tunnel barrier layer 412, and a free layer 414. The bilayerstructure of the MTJ cap layer 416 may provide similar resistance tooxidation as provided by the MTJ cap layer 316 of FIG. 3 and may exhibita larger conductivity than the MTJ cap layer 316 of FIG. 3 due to thenon-nitrified material in the first MTJ capping layer 416.

Referring to FIG. 5, a fifth particular embodiment is depicted of asystem including an MTJ device 500 including conductive nitrified metal.As illustrated, the device 500 includes an MTJ device coupled between abottom electrode 504 and a top electrode 520. The bottom electrode 504is coupled to a bottom metal wire 502, and the top electrode 520 iscoupled to a top metal wire 522. The MTJ device includes an MTJstructure 506 formed of an AFM layer 508 on the bottom electrode 504, afixed layer 510, a tunnel barrier 512, and a free layer 514. An MTJ caplayer 516 is coupled to the free layer 514 and to the top electrode 520.A sidewall protective layer 518 may be formed adjacent to the MTJstructure 516. One or more of the bottom electrode 504, the MTJ caplayer 516, and the top electrode 520 may include conductive nitrifiedmetal, such as in a bilayer structure with a bottom layer that includesnon-nitrified material and an upper layer that includes conductivenitrified metal.

As illustrated, each of the bottom electrode 504, the MTJ cap layer 516,and the top electrode 520 include a multi-layer structure with a lowerlayer including non-nitrified material and an upper layer including aconductive nitrified metal. The top electrode 520 includes a firstconductive nitrified metal, the MTJ cap layer 536 includes a secondconductive nitrified metal, and the bottom electrode 504 includes athird conductive nitrified metal. The first, second and third nitrifiedmetals may individually include tantalum nitride, titanium nitride, orany combination thereof. In a particular embodiment, the top electrode520, the MTJ cap layer 536, and the bottom electrode 504 may include acommon nitrified metal. For example, the top electrode 520, the MTJ caplayer 536, and the bottom electrode 504 may each include titaniumnitride. In other embodiments, different nitrified metals may be used inone or more of the top electrode 520, the MTJ cap layer 536, and thebottom electrode 504. For example, the top electrode 520 may includetitanium nitride and the MTJ cap layer 536 may include tantalum nitride.

The bottom electrode 504 is illustrated as including a first electrodelayer 538 that is coupled to the bottom metal wire 502 via a bottom viathrough the bottom diffusion barrier cap film. The bottom electrode 504includes a second electrode layer 540 that includes the third conductivenitrified metal. The third nitrified metal of the second bottomelectrode layer 540 exhibits similar properties as described withrespect to the nitrified metal layer of the top electrode 120 of FIG. 1and the MTJ cap layer 316 of FIG. 3, such as electrode conductivity andreduced oxide formation, which enables a larger process window andreduces cleaning required prior to depositing the AFM layer 508 on thebottom electrode 504. In a particular embodiment, the third conductivenitrified metal is tantalum nitride or titanium nitride, and thenon-nitrified material may be tantalum or titanium.

In a particular embodiment, the MTJ cap layer 516 includes a first MTJcapping layer 534 and second MTJ capping layer 536. The first MTJcapping layer 534 may consist essentially of non-nitrified material,while the second MTJ capping layer 536 comprises the second conductivenitrified metal. In a particular embodiment, the MTJ capping layer 534corresponds to the first MTJ capping layer 434 of FIG. 4, and the secondMTJ capping layer 536 corresponds to the second MTJ capping layer 436 ofFIG. 4.

In a particular embodiment, the top electrode 520 includes a firstelectrode layer 530 and a second electrode layer 532. The firstelectrode layer 530 may consist essentially of non-nitrified material,and the second electrode layer 532 comprises the first conductivenitrified metal. In a particular embodiment, the first electrode layer530 corresponds to the first electrode layer 230 of FIG.2 and the secondelectrode layer 532 corresponds to the second electrode layer 232 ofFIG. 2.

As illustrated in FIGS. 2, 4, and 5, one or more bi-layer or multi-layerstructures may be formed having an oxidation prevention conductive layerand a conductive layer, such as the top electrode 220 of FIG. 2, thebi-layer cap 416 of FIG. 4, the bi-layer bottom electrode 504, thebi-layer cap 516, and the bi-layer top electrode 520 of FIG. 5. In someembodiments, the oxidation prevention conductive layer may includenitrified materials, such as TiN or TaN as illustrative examples. Inother embodiments, one or more oxidation prevention conductive layer maynot include nitrified material and may instead include one or more othermaterials that enable conduction while reducing or preventing oxidation.As an illustrative example, a non-nitrified oxidation preventionconductive layer may include Ruthenium.

Although the devices depicted in FIGS. 1-5 are illustrated as includingmultiple components and/or layers, it will be understood to thoseskilled in the art that in other embodiments the devices may includefewer components than illustrated, may include additional components, ora combination thereof. For example, in some embodiments a top electrode,such as the top electrode 120 of FIG. 1, may be coupled to an MTJstructure, such as directly coupled to the free layer 114 of FIG. 1,without a cap layer between the top electrode and the free layer. Asanother example, MTJ structure layers such as a free layer and a fixedlayer may be synthetic layers formed of multiple sub-layers.Alternatively, or in addition, one or more additional layers such as aspin torque enhancement layer or a diffusion barrier layer may beincluded, as illustrative, non-limiting examples.

Referring to FIG. 6, a flow chart is depicted of a first embodiment of amethod of fabricating an MTJ device. The method 600 includes patterningof a bottom metal, at 602. For example, the bottom metal may be thebottom metal wire 502 of FIG. 5. A diffusion barrier cap layer isdeposited, at 604. The diffusion barrier cap layer may be a bottom capfilm deposited over the bottom metal layer, such as the bottom cap filmdeposited over the bottom metal wire 502 of FIG. 5.

Optionally, a diffusion barrier cap layer planarization may beperformed, at 606. To illustrate, a deposition of the bottom diffusionbarrier cap film over the bottom metal wire may result in an uneven orrough upper surface of the diffusion barrier cap film, due to a roughsurface of the bottom metal wire 502. As a result, the bottom diffusionbarrier cap film may be planerized to generate a smooth surface. Forexample, in embodiments where the MTJ structure is formed directly over,or at least partially overlapping, the bottom metal wire 502, adiffusion barrier cap film planarization step may enable a more uniformdeposition of electrode and MTJ film layers. A bottom via may bepatterned, at 608. For example, the bottom via may be filled by bottomelectrode material that provides an improved surface for deposition ofmetals than the diffusion barrier cap film layer.

A conductive nitride metal bilayer or single layer bottom electrodedeposit is performed, at 610. To illustrate, the nitride metal bilayermay be similar to the bottom electrode 504 having the first electrodelayer 538 and the second electrode layer 540 illustrated in FIG. 5. Asanother example, the single layer bottom electrode may be similar to thebottom electrode 204 of FIG. 2, with the addition of a nitride metal. Toillustrate, the conductive nitride metal may be tantalum nitride,titanium nitride, or other conductive nitrified metals. In a bilayerstructure, a single layer may include the conductive nitride metal,while one or more additional layers may not include a substantial amountof the conductive nitride metal.

An optional bottom electrode planarization process is performed, at 612.A pre-clean is performed, followed by an MTJ film deposit and a bilayeror single layer MTJ cap deposit, at 614. For example, a pre-clean isperformed of the bottom electrode after an optional planarization toprepare the bottom electrode for deposition of the MTJ films. Followingthe pre-clean, the MTJ film layers may be deposited to form an MTJstructure, such as the MTJ structure 506 depicted in FIG. 5. If a bottomelectrode planarization process is skipped, the MTJ film layers may bedeposited to form an MTJ structure after bottom electrode filmdeposition. After depositing the MTJ film layers, the MTJ cap layer maybe deposited, either as a bilayer, as illustrated in FIG. 5, or as asingle layer, as illustrated in FIG. 3.

The MTJ is patterned and a sidewall diffusion barrier cap film isdeposited, at 616. For example, the MTJ may be patterned by performingan MTJ photo and etch process that uses the MTJ cap layer to protect theMTJ structure and as a hardmask. Following the MTJ patterning, thesidewall diffusion barrier cap film, such as the sidewall protectivelayer 518 illustrated in FIG. 5, may be deposited.

An oxide deposit is performed, followed by a chemical mechanicalplanarization (CMP) to the top of the MTJ sidewall diffusion barrier capfilm, at 618. For example, after depositing the sidewall diffusionbarrier cap film, an oxide film may be deposited, and the CMP performedto smooth an upper surface of the MTJ device and to expose the MTJdiffusion barrier cap material of the sidewall diffusion barrier caplayer. The MTJ top is opened, at 620, and a pre-clean and bilayer orsingle layer nitride metal top electrode deposit is performed at 622. Inaddition, a temporary diffusion barrier cap layer may also be depositedover the top electrode, at 622. Depositing the bilayer nitride topelectrode may include depositing multiple electrode layers during aformation of a top electrode having a first electrode layer that may notinclude the nitrified metal and having a second electrode layer thatdoes include the conductive nitride metal, such as the top electrode 520of FIG. 5. Similarly, the single layer conductive nitride metal topelectrode deposit may include depositing a single electrode layer duringformation of a top electrode including conductive nitrified metal, suchas the top electrode 120 of FIG. 1. Top and bottom electrodes arepatterned, at 624. For example, a photolithography process may beperformed and the top electrode layer(s) and the bottom electrodelayer(s) may be etched to form the top and bottom electrodes. A lowpermittivity inter-metal dielectric (IMD) film deposit is performed anda chemical mechanical planarization (CMP) is performed, at 626.

A top via and metal patterning process is performed at 628. The top viaand metal patterning process can be combined with logic via and metalpatterning, such as when the MTJ is integrated with logic process. A topdiffusion barrier cap film is deposited, at 630. For example, the topdiffusion barrier cap film may be the top cap film layer illustrated inFIG. 5.

By including the conductive nitride metal in the bottom electrode, at610, in the MTJ cap layer, at 614, and in the top electrode, at 622,process windows may be expanded and fabrication may be performed withincreased ease and fewer processing defects due to the reduced oxidationon each of the surfaces of the conductive nitrified metals. Suchproperties enable relaxation of pre-clean requirements prior toadditional layer formation. Although in the embodiment illustrated inFIG. 6 nitrified metal may be used to reduce oxidation, in otherembodiments bi-layer or multi-layer structures may be formed having anoxidation prevention conductive layer and a conductive layer, where theoxidation prevention conductive layer may not include nitrified materialand may instead include one or more other materials that enableconduction while reducing or preventing oxidation. As an illustrativeexample, a non-nitrified oxidation prevention conductive layer mayinclude Ruthenium.

Referring to FIG. 7, a second particular embodiment of a method offorming an MTJ device is depicted and generally designated 700. Themethod 700 may include forming an MTJ cap layer on an MTJ structure, at702. The method 700 includes forming a top electrode layer over the MTJstructure, such as over the MTJ cap layer, at 708. The top electrodelayer includes a first conductive nitrified metal. Forming the MTJ caplayer may include forming a first MTJ capping layer on the MTJstructure, at 704, and forming a second MTJ capping layer over the firstMTJ capping layer, at 706. The second MTJ capping layer may include asecond conductive nitrified metal. For example, the first MTJ cappinglayer may consist essentially of tantalum and the second MTJ cappinglayer may consist essentially of tantalum nitride. As another example,the first MTJ capping layer may consist essentially of titanium and thesecond MTJ capping layer may consist essentially of titanium nitride.

Forming the top electrode layer may include forming a first electrodelayer over the MTJ cap layer, at 710. Forming the top electrode layermay also include forming a second electrode layer over the firstelectrode layer, at 712. The second electrode layer may include thefirst conductive nitrified metal. In a particular embodiment, the firstnitrified metal may comprise tantalum nitride. Alternatively, or inaddition, the first nitrified metal may include titanium nitride.

In a particular embodiment, the first electrode layer may consistessentially of tantalum and the second electrode layer may consistessentially of tantalum nitride. Alternatively, the first electrodelayer may consist essentially of titanium and the second electrodelayers consist essentially of titanium nitride.

FIG. 8 is a block diagram of a particular embodiment of a system 800including a component including MTJ structures having top electrodelayers or MTJ cap layers with nitrified metal 864. The system 800 may beimplemented in a portable electronic device and includes a processor810, such as a digital signal processor (DSP), coupled to a computerreadable medium, such as a memory 832, storing computer readableinstructions, such as software 866. The system 800 includes componentsincluding MTJ structures having top electrode layers or MTJ cap layerswith nitrified metal 864. In an illustrative example, a componentincluding MTJ structures having top electrode layers or MTJ cap layerswith nitrified metal 864 includes the MTJ structure of any of theembodiments of FIGS. 1-5, or produced in accordance with the embodimentsof FIGS. 6-7, or any combination thereof. One or more componentsincluding MTJ structures having top electrode layers or MTJ cap layerswith nitrified metal 864 may be in the processor 810 or may be aseparate device or circuitry (not shown). In a particular embodiment, asshown in FIG. 8, a component including MTJ structures having topelectrode layers or MTJ cap layers with nitrified metal 864 isaccessible to the digital signal processor (DSP) 810. In anotherparticular embodiment, the memory 832 may include an STT-MRAM memoryarray that includes components including MTJ structures having topelectrode layers or MTJ cap layers with nitrified metal 864.

A camera interface 868 is coupled to the processor 810 and also coupledto a camera, such as a video camera 870. A display controller 826 iscoupled to the processor 810 and to a display device 828. Acoder/decoder (CODEC) 834 can also be coupled to the processor 810. Aspeaker 836 and a microphone 838 can be coupled to the CODEC 834. Awireless interface 840 can be coupled to the processor 810 and to awireless antenna 842.

In a particular embodiment, the processor 810, the display controller826, the memory 832, the CODEC 834, the wireless interface 840, and thecamera interface 868 are included in a system-in-package orsystem-on-chip device 822. In a particular embodiment, an input device830 and a power supply 844 are coupled to the system-on-chip device 822.Moreover, in a particular embodiment, as illustrated in FIG. 8, thedisplay device 828, the input device 830, the speaker 836, themicrophone 838, the wireless antenna 842, the video camera 870, and thepower supply 844 are external to the system-on-chip device 822. However,each of the display device 828, the input device 830, the speaker 836,the microphone 838, the wireless antenna 842, the video camera 870, andthe power supply 844 can be coupled to a component of the system-on-chipdevice 822, such as an interface or a controller.

The foregoing disclosed devices and functionalities (such as the devicesof FIGS. 1-5, the methods of FIGS. 6-7, or any combination thereof) maybe designed and configured into computer files (e.g., RTL, GDSII,GERBER, etc.) stored on computer readable media. Some or all such filesmay be provided to fabrication handlers who fabricate devices based onsuch files. Resulting products include semiconductor wafers that arethen cut into semiconductor die and packaged into a semiconductor chip.The semiconductor chips are then employed in electronic devices. FIG. 9depicts a particular illustrative embodiment of an electronic devicemanufacturing process 900.

Physical device information 902 is received in the manufacturing process900, such as at a research computer 906. The physical device information902 may include design information representing at least one physicalproperty of a semiconductor device, such as an MTJ device as illustratedin any of FIGS. 1-5 or formed in accordance with any of FIGS. 6-7. Forexample, the physical device information 902 may include physicalparameters, material characteristics, and structure information that isentered via a user interface 904 coupled to the research computer 906.The research computer 906 includes a processor 908, such as one or moreprocessing cores, coupled to a computer readable medium such as a memory910. The memory 910 may store computer readable instructions that areexecutable to cause the processor 908 to transform the physical deviceinformation 902 to comply with a file format and to generate a libraryfile 912.

In a particular embodiment, the library file 912 includes at least onedata file including the transformed design information. For example, thelibrary file 912 may include a library of semiconductor devicesincluding an MTJ device as illustrated in any of FIGS. 1-5 or formed inaccordance with any of FIGS. 6-7, that is provided for use with anelectronic design automation (EDA) tool 920.

The library file 912 may be used in conjunction with the EDA tool 920 ata design computer 914 including a processor 916, such as one or moreprocessing cores, coupled to a memory 918. The EDA tool 920 may bestored as processor executable instructions at the memory 918 to enablea user of the design computer 914 to design a circuit using the MTJdevice as illustrated in any of FIGS. 1-5 or formed in accordance withany of FIGS. 6-7, of the library file 912. For example, a user of thedesign computer 914 may enter circuit design information 922 via a userinterface 924 coupled to the design computer 914. The circuit designinformation 922 may include design information representing at least onephysical property of a semiconductor device, such as the MTJ device asillustrated in any of FIGS. 1-5 or formed in accordance with any ofFIGS. 6-7. To illustrate, the circuit design property may includeidentification of particular circuits and relationships to otherelements in a circuit design, positioning information, feature sizeinformation, interconnection information, or other informationrepresenting a physical property of a semiconductor device.

The design computer 914 may be configured to transform the designinformation, including the circuit design information 922, to complywith a file format.

To illustrate, the file formation may include a database binary fileformat representing planar geometric shapes, text labels, and otherinformation about a circuit layout in a hierarchical format, such as aGraphic Data System (GDSII) file format. The design computer 914 may beconfigured to generate a data file including the transformed designinformation, such as a GDSII file 926 that includes informationdescribing the MTJ device as illustrated in any of FIGS. 1-5 or formedin accordance with any of FIGS. 6-7, in addition to other circuits orinformation. To illustrate, the data file may include informationcorresponding to a system-on-chip (SOC) that includes the MTJ device asillustrated in any of FIGS. 1-5 or formed in accordance with any ofFIGS. 6-7 and that also includes additional electronic circuits andcomponents within the SOC.

The GDSII file 926 may be received at a fabrication process 928 tomanufacture the MTJ device as illustrated in any of FIGS. 1-5 or formedin accordance with any of FIGS. 6-7, according to transformedinformation in the GDSII file 926. For example, a device manufactureprocess may include providing the GDSII file 926 to a mask manufacturer930 to create one or more masks, such as masks to be used forphotolithography processing, illustrated as a representative mask 932.The mask 932 may be used during the fabrication process to generate oneor more wafers 934, which may be tested and separated into dies, such asa representative die 936. The die 936 includes a circuit including theMTJ device as illustrated in any of FIGS. 1-5 or formed in accordancewith any of FIGS. 6-7.

The die 936 may be provided to a packaging process 938 where the die 936is incorporated into a representative package 940. For example, thepackage 940 may include the single die 936 or multiple dies, such as asystem-in-package (SiP) arrangement. The package 940 may be configuredto conform to one or more standards or specifications, such as JointElectron Device Engineering Council (JEDEC) standards.

Information regarding the package 940 may be distributed to variousproduct designers, such as via a component library stored at a computer946. The computer 946 may include a processor 948, such as one or moreprocessing cores, coupled to a memory 950. A printed circuit board (PCB)tool may be stored as processor executable instructions at the memory950 to process PCB design information 942 received from a user of thecomputer 946 via a user interface 944. The PCB design information 942may include physical positioning information of a packaged semiconductordevice on a circuit board, the packaged semiconductor devicecorresponding to the package 940 including the MTJ device as illustratedin any of FIGS. 1-5 or formed in accordance with any of FIGS. 6-7.

The computer 946 may be configured to transform the PCB designinformation 942 to generate a data file, such as a GERBER file 952 withdata that includes physical positioning information of a packagedsemiconductor device on a circuit board, as well as layout of electricalconnections such as traces and vias, where the packaged semiconductordevice corresponds to the package 940 including the MTJ device asillustrated in any of FIGS. 1-5 or formed in accordance with any ofFIGS. 6-7. In other embodiments, the data file generated by thetransformed PCB design information may have a format other than a GERBERformat.

The GERBER file 952 may be received at a board assembly process 954 andused to create PCBs, such as a representative PCB 956, manufactured inaccordance with the design information stored within the GERBER file952. For example, the GERBER file 952 may be uploaded to one or moremachines for performing various steps of a PCB production process. ThePCB 956 may be populated with electronic components including thepackage 940 to form a representative printed circuit assembly (PCA) 958.

The PCA 958 may be received at a product manufacture process 960 andintegrated into one or more electronic devices, such as a firstrepresentative electronic device 962 and a second representativeelectronic device 964. As an illustrative, non-limiting example, thefirst representative electronic device 962, the second representativeelectronic device 964, or both, may be selected from the group of a settop box, a music player, a video player, an entertainment unit, anavigation device, a communications device, a personal digital assistant(PDA), a fixed location data unit, and a computer. As anotherillustrative, non-limiting example, one or more of the electronicdevices 962 and 964 may be remote units such as mobile phones, hand-heldpersonal communication systems (PCS) units, portable data units such aspersonal data assistants, global positioning system (GPS) enableddevices, navigation devices, fixed location data units such as meterreading equipment, or any other device that stores or retrieves data orcomputer instructions, or any combination thereof. Although FIG. 9illustrates remote units according to teachings of the disclosure, thedisclosure is not limited to these exemplary illustrated units.Embodiments of the disclosure may be suitably employed in any devicewhich includes active integrated circuitry including memory and on-chipcircuitry.

Thus, MTJ devices as illustrated in any of FIGS. 1-5 or formed inaccordance with any of FIGS. 6-7, may be fabricated, processed, andincorporated into an electronic device, as described in the illustrativeprocess 900. One or more aspects of the embodiments disclosed withrespect to FIGS. 1-8 may be included at various processing stages, suchas within the library file 912, the GDSII file 926, and the GERBER file952, as well as stored at the memory 910 of the research computer 906,the memory 918 of the design computer 914, the memory 950 of thecomputer 946, the memory of one or more other computers or processors(not shown) used at the various stages, such as at the board assemblyprocess 954, and also incorporated into one or more other physicalembodiments such as the mask 932, the die 936, the package 940, the PCA958, other products such as prototype circuits or devices (not shown),or any combination thereof. For example, the GDSII file 926 or thefabrication process 928 can include a computer readable tangible mediumstoring instructions executable by a computer, a controller of amaterial deposition system, or other electronic device, the instructionsincluding instructions that are executable by a processor of thecomputer or controller to initiate formation of an MTJ device asillustrated in any of FIGS. 1-5 or formed in accordance with any ofFIGS. 6-7. For example, the instructions may include instructions thatare executable by a computer to initiate formation of a top electrodelayer over an MTJ structure, the top electrode layer including a firstnitrified metal, and may further include instructions that areexecutable by the computer to initiate formation of an MTJ cap layer onthe MTJ structure, where the top electrode layer is formed over the MTJcap layer. Although various representative stages of production from aphysical device design to a final product are depicted, in otherembodiments fewer stages may be used or additional stages may beincluded. Similarly, the process 900 may be performed by a singleentity, or by one or more entities performing various stages of theprocess 900.

Those of skill would further appreciate that the various illustrativelogical blocks, configurations, modules, circuits, and method stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software executed by aprocessing unit, or combinations of both. Various illustrativecomponents, blocks, configurations, modules, circuits, and steps havebeen described above generally in terms of their functionality. Whethersuch functionality is implemented as hardware or executable processinginstructions depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in random access memory (RAM), amagnetoresistive random access memory (MRAM), a spin-torque-transfermagnetoresistive random access memory (STT-MRAM), flash memory,read-only memory (ROM), programmable read-only memory (PROM), erasableprogrammable read-only memory (EPROM), electrically erasableprogrammable read-only memory (EEPROM), registers, hard disk, aremovable disk, a compact disc read-only memory (CD-ROM), or any otherform of storage medium known in the art. An exemplary storage medium iscoupled to the processor such that the processor can read informationfrom, and write information to, the storage medium. In the alternative,the storage medium may be integral to the processor. The processor andthe storage medium may reside in an application-specific integratedcircuit (ASIC). The ASIC may reside in a computing device or a userterminal. In the alternative, the processor and the storage medium mayreside as discrete components in a computing device or user terminal.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the principles defined hereinmay be applied to other embodiments without departing from the scope ofthe disclosure. Thus, the present disclosure is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope possible consistent with the principles and novel features asdefined by the following claims.

1. A method of forming a magnetic tunnel junction (MTJ) device, themethod comprising: forming a top electrode layer over an MTJ structurecomprising a first nitrified metal.
 2. The method of claim 1, whereinthe first nitrified metal comprises tantalum nitride (TaN). 3 The methodof claim 1, wherein the first nitrified metal comprises titanium nitride(TiN).
 4. The method of claim 1, further comprising forming an MTJ caplayer on the MTJ structure, wherein the top electrode layer is formedover the MTJ cap layer.
 5. The method of claim 4, wherein forming thetop electrode layer comprises: forming a first electrode layer over theMTJ cap layer; and forming a second electrode layer over the firstelectrode layer, the second electrode layer comprising the firstnitrified metal.
 6. The method of claim 4, wherein the MTJ cap layercomprises a second nitrified metal.
 7. The method of claim 6, whereinthe second nitrified metal comprises tantalum nitride (TaN).
 8. Themethod of claim 6, wherein the second nitrified metal comprises titaniumnitride (TiN).
 9. The method of claim 6, wherein forming the MTJ caplayer comprises: forming a first MTJ capping layer on the MTJ structure;and forming a second MTJ capping layer over the first MTJ capping layer,the second MTJ capping layer comprising the second nitrified metal. 10.The method of claim 4, wherein forming the MTJ cap layer on the MTJstructure and forming the top electrode layer over the MTJ cap layer areinitiated by a processor integrated into a computer or a controller of amaterial deposition system.
 11. An apparatus comprising: a magnetictunnel junction (MTJ) device comprising: an MTJ structure; and a topelectrode layer coupled to the MTJ structure comprising a firstnitrified metal.
 12. The apparatus of claim 11, wherein the firstnitrified metal comprises tantalum nitride (TaN).
 13. The apparatus ofclaim 11, wherein the first nitrified metal comprises titanium nitride(TiN).
 14. The apparatus of claim 11, wherein the MTJ device furthercomprises an MTJ cap layer between the MTJ structure and the topelectrode.
 15. The apparatus of claim 14, wherein the top electrodelayer comprises: a first electrode layer coupled to the MTJ cap layer;and a second electrode layer adjacent to the first electrode layer; saidsecond electrode layer comprising the first nitrified metal and saidfirst electrode layer consisting essentially of a material other thanthe first nitrified metal.
 16. The apparatus of claim 14, wherein theMTJ cap layer comprises a second nitrified metal.
 17. The apparatus ofclaim 16, wherein the MTJ cap layer comprises: a first MTJ capping layercoupled to the MTJ structure; and a second MTJ capping layer adjacent tothe first MTJ capping layer; said second MTJ capping layer comprisingthe second nitrified metal and said first MTJ capping layer consistingessentially of a material other than the second nitrified metal.
 18. Theapparatus of claim 11 integrated in at least one semiconductor die. 19.The apparatus of claim 18, further comprising a device selected from thegroup consisting of a set top box, a music player, a video player, anentertainment unit, a navigation device, a communications device, apersonal digital assistant (PDA), a fixed location data unit, and acomputer, into which the semiconductor die is integrated.
 20. Anapparatus comprising: a magnetic tunnel junction (MTJ) devicecomprising: an MTJ structure; and an MTJ cap layer coupled to the MTJstructure, the MTJ cap layer comprising a single layer, that comprises anitrified metal.
 21. The apparatus of claim 20, wherein the nitrifiedmetal comprises tantalum nitride (TaN).
 22. The apparatus of claim 20,wherein the nitrified metal comprises titanium nitride (TiN).
 23. Theapparatus of claim 20, wherein the MTJ device further comprises anelectrode layer coupled to the MTJ cap layer, the electrode layercomprising a second nitrified metal.
 24. The apparatus of claim 20integrated in at least one semiconductor die.
 25. The apparatus of claim24, further comprising a device selected from the group consisting of aset top box, a music player, a video player, an entertainment unit, anavigation device, a communications device, a personal digital assistant(PDA), a fixed location data unit, and a computer, into which thesemiconductor die is integrated.
 26. An apparatus comprising: a magnetictunnel junction (MTJ) device comprising: an MTJ structure; and means forcoupling the MTJ structure to a metal wire, the means for couplingcomprising a first nitrified metal.
 27. The apparatus of claim 26,wherein the MTJ device further comprises capping means, wherein the MTJstructure is coupled to the metal wire via the capping means, andwherein the capping means comprises a second nitrified metal.
 28. Theapparatus of claim 26, wherein the means for coupling comprises: a firstelectrode layer; and a second electrode layer adjacent to the firstelectrode layer, wherein the second electrode layer comprises the firstnitrified metal and wherein the first electrode layer is formed of anon-nitrified metal.
 29. The apparatus of claim 26 integrated in atleast one semiconductor die.
 30. The apparatus of claim 29, furthercomprising a device selected from the group consisting of a set top box,a music player, a video player, an entertainment unit, a navigationdevice, a communications device, a personal digital assistant (PDA), afixed location data unit, and a computer, into which the semiconductordie is integrated.
 31. A method of forming a magnetic tunnel junction(MTJ) device, the method comprising: a first step for forming an MTJ caplayer on an MTJ structure; and a second step for forming a top electrodelayer over the MTJ cap layer, the top electrode layer comprising a firstnitrified metal.
 32. The method of claim 31, wherein the first nitrifiedmetal comprises tantalum nitride (TaN).
 33. The method of claim 31,wherein the first nitrified metal comprises titanium nitride (TiN). 34.The method of claim 31, wherein the MTJ cap layer comprises a secondnitrified metal.
 35. The method of claim 31, wherein the first step andthe second step are initiated by a processor integrated into anelectronic device.
 36. A computer readable medium storing instructionsexecutable by a computer, the instructions comprising: instructions thatare executable by the computer to initiate formation of a top electrodelayer over an MTJ structure, the top electrode layer comprising a firstnitrified metal.
 37. The computer readable medium of claim 36, whereinthe first nitrified metal comprises tantalum nitride (TaN) or titaniumnitride (TiN).
 38. The computer readable medium of claim 36, wherein theinstructions further comprise instructions that are executable by thecomputer to initiate formation of an MTJ cap layer on the MTJ structure,wherein the top electrode layer is formed over the MTJ cap layer. 39.The computer readable medium of claim 38, wherein the MTJ cap layercomprises a second nitrified metal.
 40. A method comprising: receivingdesign information representing at least one physical property of asemiconductor device, the semiconductor device comprising: an MTJstructure; and a top electrode layer coupled to the MTJ structure, thetop electrode layer comprising a nitrified metal; transforming thedesign information to comply with a file format; and generating a datafile including the transformed design information.
 41. The method ofclaim 40, wherein the data file includes a GDSII format.
 42. The methodof claim 40, wherein the data file includes a GERBER format.
 43. Amethod comprising: receiving a data file comprising design informationcorresponding to a semiconductor device; and fabricating thesemiconductor device according to the design information, wherein thesemiconductor device comprises: an MTJ structure; and a top electrodelayer coupled to the MTJ structure, the top electrode layer comprising anitrified metal.
 44. The method of claim 43, wherein the data file has aGDSII format.
 45. A method comprising: receiving a data file comprisingdesign information comprising physical positioning information of apackaged semiconductor device on a circuit board; and manufacturing thecircuit board configured to receive the packaged semiconductor deviceaccording to the design information, wherein the packaged semiconductordevice comprises: an MTJ structure; and a top electrode layer coupled tothe MTJ structure, the top electrode layer comprising a nitrified metal.46. The method of claim 45, further comprising integrating the circuitboard into a device selected from the group consisting of a set top box,a music player, a video player, an entertainment unit, a navigationdevice, a communications device, a personal digital assistant (PDA), afixed location data unit, and a computer.
 47. An apparatus comprising: amagnetic tunnel junction (MTJ) device comprising: an MTJ structure; anMTJ cap layer coupled to the MTJ structure; and a top electrode layercoupled to the MTJ cap layer, the top electrode layer comprising: anoxidation prevention conductive layer; and a conductive layer.
 48. Theapparatus of claim 47, wherein the oxidation prevention conductive layerincludes a nitrified metal.
 49. The apparatus of claim 47, wherein theoxidation prevention conductive layer does not include nitrifiedmaterial.